Controls on the epilimnetic phosphorus concentration in small temperate lakes

Abstract Built in 1959, Lake Paranoá, in Brasilia, Brazil, has been undergoing an accelerated process of nutrient enrichment, due to inputs of inadequately treated raw sewage, generated by a population of 600,000 inhabitants. Consequently, it shows high nutrient content (40 µg/L of total phosphorus and 1800 µg/L of total nitrogen), low transparency (0.65 m) and high levels of chlorophyll a (65 µg/L), represented mainly by Cylindrospermopsis raciborskii and sporadic bloom of Microcystis aeruginosa, which is being combatted with copper sulphate. With the absence of seasonality and a vertical distribution which is not very evident, the horizontal pattern assumes great importance in this reservoir, in which five compartments stand out. Based on this segmentation and on the identification of the total phosphorus parameter as the limiting factor for algal growth, mathematical models were developed which demonstrate the need for advanced treatment of all the sewage produced in its drainage basin. With this, it is expected that a process of restoration will be initiated, with a decline in total phosphorus concentration to readings below 25 µg/L. Additional measures are proposed to accelerate this process.

Download Full-text

Phosphorus Leaching Under Cut Grassland

Water Science & Technology ◽

10.2166/wst.1999.0530 ◽

1999 ◽

Vol 39 (12) ◽

pp. 63-67 ◽

Cited By ~ 5

Author(s):

B. L. Turner ◽

P. M. Haygarth

Keyword(s):

Surface Waters ◽

Large Scale ◽

Agricultural Land ◽

Algal Growth ◽

Soil Types ◽

P Fractions ◽

Inorganic P ◽

Potential Source ◽

Significant Mechanism ◽

Total P

Phosphorus (P) transfer from agricultural land to surface waters can contribute to eutrophication, excess algal growth and associated water quality problems. Grasslands have a high potential for P transfer, as they receive P inputs as mineral fertiliser and concentrates cycled through livestock manures. The transfer of P can occur through surface and subsurface pathways, although the capacity of most soils to fix inorganic P has meant that subsurface P transfer by leaching mechanisms has often been perceived as negligible. We investigated this using large-scale monolith lysimeters (135 cm deep, 80 cm diameter) to monitor leachate P under four grassland soil types. Leachate was collected during the 1997–98 drainage year and analysed for a range of P fractions. Mean concentrations of total P routinely exceeded 100 μg l−1 from all soil types and, therefore, exceeded P concentrations above which eutrophication and algal growth can occur. The majority of the leachate P was in algal-available Mo-reactive (inorganic) forms, although a large proportion occurred in unreactive (organic) forms. We suggest that subsurface transfer by leaching can represent a significant mechanism for agricultural P transfer from some soils and must be given greater consideration as a potential source of diffuse P pollution to surface waters.

Download Full-text

Algal growth potential (AGP) of coastal north Patagonian waters: limiting nutrients and prospects for commercial mussel production

Deep Sea Research Part B Oceanographic Literature Review ◽

10.1016/0198-0254(82)90413-7 ◽

1982 ◽

Vol 29 (12) ◽

pp. 804

Keyword(s):

Algal Growth ◽

Growth Potential ◽

Limiting Nutrients ◽

Algal Growth Potential

Download Full-text

Episodic fresh surface waters in the Eocene Arctic Ocean

Nature ◽

10.1038/nature04692 ◽

2006 ◽

Vol 441 (7093) ◽

pp. 606-609 ◽

Cited By ~ 209

Author(s):

Henk Brinkhuis ◽

◽

Stefan Schouten ◽

Margaret E. Collinson ◽

Appy Sluijs ◽

...

Keyword(s):

Arctic Ocean ◽

Surface Waters ◽

Fresh Surface

Download Full-text

Radiocesium in the Taiwan Strait and the Kuroshio east of Taiwan from 2018 to 2019

Scientific Reports ◽

10.1038/s41598-021-01895-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Wei-Jen Huang ◽

Ming-Ta Lee ◽

Kuei-Chen Huang ◽

Kai-Jung Kao ◽

Ming-An Lee ◽

...

Keyword(s):

Water Column ◽

Surface Waters ◽

Half Life ◽

North Pacific Ocean ◽

Taiwan Strait ◽

Depth Range ◽

Near Surface ◽

Activity Concentrations ◽

The Taiwan Strait ◽

The Kuroshio

AbstractThe release of anthropogenic radiocesium to the North Pacific Ocean (NPO) has occurred in the past 60 years. Factors controlling 137Cs (half-life, 30.2 year) and 134Cs (half-life, 2.06 year) activity concentrations in the Kuroshio east of Taiwan and the Taiwan Strait (latitude 20° N–27° N, longitude 116° E–123° E) remain unclear. This study collected seawater samples throughout this region and analyzed 134Cs and 137Cs activity concentrations between 2018 and 2019. A principal component analysis (PCA) was performed to analyze the controlling factors of radiocesium. Results of all 134Cs activity concentrations were below the detection limit (0.5 Bq m−3). Analyses of water column 137Cs profiles revealed a primary concentration peak (2.1–2.2 Bq m−3) at a depth range of 200–400 m (potential density σθ: 25.3 to 26.1 kg m−3). The PCA result suggests that this primary peak was related to density layers in the water column. A secondary 137Cs peak (1.90 Bq m−3) was observed in the near-surface waters (σθ = 18.8 to 21.4 kg m−3) and was possibly related to upwelling and river-to-sea mixing on the shelf. In the Taiwan Strait, 137Cs activity concentrations in the near-surface waters were higher in the summer than in the winter. We suggest that upwelling facilitates the vertical transport of 137Cs at the shelf break of the western NPO.

Download Full-text

The role of methanotrophy in the microbial carbon metabolism of temperate lakes

Nature Communications ◽

10.1038/s41467-021-27718-2 ◽

2022 ◽

Vol 13 (1) ◽

Author(s):

Paula C. J. Reis ◽

Shoji D. Thottathil ◽

Yves T. Prairie

Keyword(s):

Water Column ◽

Carbon Metabolism ◽

Volume Fraction ◽

Specific Activity ◽

Freshwater Ecosystems ◽

Carbon Consumption ◽

Temperate Lakes ◽

Relative Contribution ◽

Methane Oxidizing Bacteria ◽

Microbial Carbon

AbstractPrevious stable isotope and biomarker evidence has indicated that methanotrophy is an important pathway in the microbial loop of freshwater ecosystems, despite the low cell abundance of methane-oxidizing bacteria (MOB) and the low methane concentrations relative to the more abundant dissolved organic carbon (DOC). However, quantitative estimations of the relative contribution of methanotrophy to the microbial carbon metabolism of lakes are scarce, and the mechanism allowing methanotrophy to be of comparable importance to DOC-consuming heterotrophy remained elusive. Using incubation experiments, microscopy, and multiple water column profiles in six temperate lakes, we show that MOB play a much larger role than their abundances alone suggest because of their larger cell size and higher specific activity. MOB activity is tightly constrained by the local methane:oxygen ratio, with DOC-rich lakes with large hypolimnetic volume fraction showing a higher carbon consumption through methanotrophy than heterotrophy at the whole water column level. Our findings suggest that methanotrophy could be a critical microbial carbon consumption pathway in many temperate lakes, challenging the prevailing view of a DOC-centric microbial metabolism in these ecosystems.

Download Full-text

Phase Fractionation of Chemical Elements During the Formation of Ice in Fresh Surface Waters

Doklady Earth Sciences ◽

10.1134/s1028334x20050207 ◽

2020 ◽

Vol 492 (1) ◽

pp. 327-332

Author(s):

A. V. Savenko ◽

V. S. Savenko ◽

O. S. Pokrovsky

Keyword(s):

Surface Waters ◽

Chemical Elements ◽

Fresh Surface

Download Full-text

Feces from Piscivorous and Herbivorous Birds Stimulate Differentially Phytoplankton Growth

Water ◽

10.3390/w11122567 ◽

2019 ◽

Vol 11 (12) ◽

pp. 2567 ◽

Cited By ~ 4

Author(s):

Jolita Petkuviene ◽

Diana Vaiciute ◽

Marija Katarzyte ◽

Iveta Gecaite ◽

Giorgio Rossato ◽

...

Keyword(s):

Heterotrophic Bacteria ◽

Algal Growth ◽

Major Effect ◽

Phytoplankton Growth ◽

Curonian Lagoon ◽

Phosphorus Concentration ◽

Direct Role ◽

Algal Groups ◽

Reactive Phosphorus

Aquatic birds may impact shallow ecosystems via organic and nutrient enrichment with feces. Such input may alleviate nutrient limitation, unbalance their ecological stoichiometry, and stimulate primary production. Herbivorous and piscivorous birds may produce different effects on aquatic ecosystems due to different physiology, diet and feces elemental composition. We analyze the effects of droppings from swans (herbivorous) and cormorants (piscivorous) on phytoplankton growth via a laboratory experiment. These birds are well represented in the Curonian Lagoon, where they form large colonies. As this lagoon displays summer algal hyper-blooms, we hypothesize an active, direct role of birds via defecation on algal growth. Short-term incubations of phytoplankton under low and high feces addition produces different stimulation of algal growth, significantly higher with high inputs of cormorant feces. The latter produces a major effect on reactive phosphorus concentration that augments significantly, as compared to treatments with swan feces, and determines an unbalanced, N-limited stoichiometry along with the duration of the experiment. During the incubation period, the dominant algal groups switch from blue-green to green algae, but such switch is independent of the level of feces input and from their origin. Heterotrophic bacteria also are stimulated by feces addition, but their increase is transient.

Download Full-text